Lapper for carbide tipped tools



M 5 K. L. LINDMARK 2,663,978

LAPPER FOR CARBIDE TIPPED TOOLS Filed Nov. 3. 1952 2 Sheets-Sheet 1 Karl Lin cimark Dec. 29, 1953 K. LINDMARK LAPPER FOR CARBIDE TIPPED TOOLS 2 Sheets-Sheet 2 Filed Nov. 3, 1952 that it may be easily removed and replaced when worn beyond further use. In like manner, if the belt requires jogging one way or the other to a central position on pulley l4 and wheel 25, that can be done readily by releasing the tension in the manner just described.

The wheel 20 and abrasive: belt [9 cooperate to provide an endless unyielding precision lapping surface on which to lap or polish on the arcuate contour of the wheel to obtain a microflnish on the tip of a welded carbide tool bit like that indicated at 35 in Fig.2. The bit 35 is mounted on a tool support or slide 36 and sometimes it is positioned at a desired angle by abutment alongside a protractor slidable back and forth in a groove 36' extending crosswise of the slide parallel to the working face of the abrasive belt I9. The tool support 36 is adjustable in and out toward and away from the belt and wheel on a table 31 carried on a vertically adjustable pillar 38, the in and out adjustment being obtained by means of a screw 39 rotatable in a bearing 40 on the support 36 and threading in a hole in the table 31. The angle of the surface 4| lapped so accurately on the tip of the tool bit 35 is determined by the elevation of the pillar 38 and hence the support 36 with respect to the working face of the wheel, it being manifest from an inspection of Fig. 2, in which the top of the support 36 on which the tool bit 35 rests is shown disposed in the plane of the horizontal line e passed through the center of the wheel 20, that the higher the elevation of the surface 4| lapped on this machine is on a radius determined by the radius of the wheel 26, that radius is large enough in relation to the thickness of the tool bit 35 for the surface 41 to be considered substantially flat. Merely by way of example but not in any sense as indicating a limitation on this invention, I may state that the wheel 20 in the machine herein shown is of a 7-inch radius and I have found that this gives good results. The important features, as I at present see them, are:

(l) The lineal speed of the abrasive belt l9;

(2) The type of abrasive belt 19;

(3) The type of cooperating wheel 20, and

(4) The relationship of the tool support 36 to the contour of the wheel 20 so as to obtain the proper angularity of the surface 4| on the carbide tipped tool bit 35.

The abrasive belt l9 and wheel 20 combination replace the so-called diamond wheels,

which are made of diamond chips or dust. This .novel combination does a much better job using far less expensive abrasive belts l9, like the silicon carbide belts that were used heretofore only for polishing glass, ceramics, and nonferrous materials. There again, the mention of silicon carbide should not be taken as in any sense a limitation on the invention, inasmuch as other abrasive materials could doubtlessly be used to equal, if not better, advantage. The belt I9 is preferably, though not necessarily, one constructed with a cloth backing and made quite thin and pliable and without any appreciable variation in thickness throughout the length thereof, that is, without any overlapping of ends. Inasmuch as the machine must be constructed so that the periphery of the wheel will be true and have a hard surface, because there must be no cushioning action, the wheel 20 is preferably 4 metal dust and safety guard, only a portion of which is indicated at 44 in Fig. 2, is preferably provided suitably attached to the table I!) and enclosing the major portion of the wheel 20 and pulley l4 and the abrasive belt l9 operating thereon, leaving exposed for performance of the lapping operation a portion of the front of the wheel 20 above and below the tool support 36. Dust discharged downwardly from the front of the wheel is conducted through the passage 45 into a pan 46 that is removably suspended on the front of the machine, as indicated at 41. Any suitable precision bearing support of the kind shown may be provided for the wheel 20, it being, of course, very important that the periphery 43 of rim 42 be truly concentric to the axis of rotation, because its trueness is the basis of cast iron or meehanite having a wide fiat rim 7 42 with a smooth true periphery 43. A sheet of the micro-finishes lapped on the tool bits.

The pillar 38 supporting the table 31 is slidable in a vertical guide bearing 48 provided on the front end of the table I0 and has a keyway 49 in which the inner end of a screw 50 is slidably received to hold the pillar against turning, and, when the screw is tightened, lock the pillar in an adjusted position. An axial hole 5| provided in the lower end of the pillar is threaded and receives a pillar adjusting screw 52 that is swivelled in a bearing 53 for rotation with a hand wheel 54. This hand wheel is graduated on the periphery from zero to and the threads on the screw 52 are so related to these graduations that one complete revolution of the wheel means a vertical adjustment of 125, namely, inch. The pillar 38 has graduations thereon in eighths of an inch, so that the operator can tell partly from the reading on the pillar 36 and partly by reference to the reading on the wheel 54, what the machine is set for, down to a thousandth of an inch. The wheel 54, of course, turns with reference to an index mark M on the front of the table l0, where the reading on the wheel 54 is taken. The screw 56 is loosened whenever the height adjustment of the tool support 36 is to be changed, and this screw is tightened again after such an adjustment.

Referring to Figs. 3 and 4, the are 43 represents a portion of the periphery of the rim 42 of wheel 26 with the abrasive belt thereon, as indicated at IS. The dimension 55 is what appears on pillar 38 when the tool support is at zero elevation-namely, at line cf, Fig. 2. The dimensions indicated at 56 are elevations above the horizontal plane of the line e for a series of angles 545". In other words, a line drawn tangent to the arc 43 at any one of these scaled points makes an angle A to the vertical equal to that indicated adjacent the dimension, the angle A illustrated in Fig. 3 being 15. Now, referring to the table 51 shown in Fig. 4, it will be seen that for each angle from 5 to 15 there is a series of dimensions 58, and that these are in columns under the headings A1", /8, etc., to 2", which refer to tool height or thickness. The operator, as directed in the Instructions 59, first determines the tool height; then he sets the pillar 38 to the height shown in the table under that tool height. Thus, if it is say a /4" tool bit the dimension indicated for a 5 angle is 1.750. That checks with Fig. 3 because 1.390+.610=2.000 and 2.000.250= 1.750. The slide 36 is accordingly set very accurately to lap the specified angle.

In conclusion, attention is called in Figs. 1 and 2 to an eccentric 60 on the end of a stub shaft 6! mounted in a bearing 62 carried by table l6 as a projection on the wheel support 63. A lever 64 is aetespvs ti-attach'ed: to the -shaft'l '6 if and is shown win Fig. 2 .in *raised operative position hOlding eccentric 6 0 frictionally engageduwith ther inner. periphery of therim dl to stop-rotation of=the wheel 20. The lever 'ifi l is otherwise swung downwardly, into. :Jabutment with, theutable' l0 .:holding.- eccentrio 60 in retracted relationship ztoithe rim 20f the wvheel :20. Quick.- stoppage: :of: .thezwheel saves-:time' for -the operatorwhen a belti-l 9:is worn and:has;to be .1 replaced.

I -=It' is. believed:theiforegoing:description conveys agoodunderstanding; -therobj ectseandiadvanitages 10f :myinvention. ..:.'Ihe:appended. claims have been drawn-'torcover all: legitimate modifica- ....tions andadaptations.

fclaim .1. ;In combination; anrendlesssabrasiverbelt of ms'uitable 'width, ai suitably. .rotatablymsupported wheel of appreciable radius having azrimnwith a o'saidbeltv operates underitensicnymeans fond-riv- -:.:ing said belt and wheel; a work supporthaving a u-surface in a 7 plane parallel $0. a radius -';ofi said :4 wheel on which atool-bit :the'tipof which-is-lto be lapped by contact with:said...abrasivessbelt; is.

adapted toflbeicarried, a pillar on top of which said support. is carried for. adjustment in a directi'on parallel to atangenttosaidwheel; aguide for said'pillar,..'and:.means for adjusting said pillariin-said guide.

v 2. The combination recited in claim .1,-.-wherein thermeans for driving. saidabrasive belt comr prises apulley on a drivenshaft, the-combinai .tion.including a support for-said shaft oscillatably adjustable on an axis'par'allel to azradius of the wheel and passing through the center of the shaft at the-middleof--=the-'pul1ey, and screw threaded adjusting meansi'connected with said 'shaft support to adjust it slightly in either direction to secure straight running of the belt.

3. The combination set forth in claim 1 wherein the means for driving the abrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as to swing away from the wheel to apply tension to the belt, said base plate being oscillatably adjustable on an axis parallel to a radius of the wheel and passing through the center of the shaft at the middle of the pulley, and screw threaded adjusting means connected with said base plate to adjust it slightly in either direction to secure straight running of the belt.

4. The combination set forth in claim 1 wherein the means for driving the abrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as to swing away from the wheel to apply tension to the belt, said base plate being oscillatably adjustable on an axis parallel to a radius of the wheel and passing through the center of the shaft at the middle of the pulley, screw threaded adjusting means connected with said base plate to adjust it slightly in either direction to secure straight running of the belt, and manually operable means for raising said motor base relative to said base plate to release tension on the abrasive belt.

5. The combination set forth in claim 1 wherein the means for driving the abrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as to swing away from the wheel to apply tension to the belt, said base plate being oscillatably adjustable on an axis parallel to a radius of the wheel and passing a -zwide' fiat:smootheunyielding peripherygon- "which 1 i.throughrthezcenteri ofcthe: shaft :atsthe middle-of the pulley, screw threaded adjustingsimeanszconnected With'i-Sflld base splateztopzadjust;it slightly i'llhe -combinationrof'iclaim 1 whereimt-said w work:supportirlcludes.a slide:omwhicl r'theawork Si carried adjustablexin a-directionaatright-angles .stoxthezpillarxand :parallelstmthe radius LofQsaid wheelztowardand awayt-fromrthe. periphery ofathe wheel.

:senting' different micrometer measurements'iiin which there is correlated with the =angle=of=-lapping desired the predeterminedmicrometermeasurement for pillar adjustmentfor each of a's'eries of tool bits of differentthicknesses.

8;A' inachinefor lapping a micro finish on the tip of a carbide tipped-"tool comprising in combination, an. endless abrasive belt-of suitable width and uniform thickness through-01111,: said belt carrying an abrasivefirmateriallIl"-fl'1'le1y 1 divided form1on its outer'surface; a suitablyrotatspeed, and meansfor adjustably supporting a tool bit to be lappedpon; the tip.so'ithat.the;bit is adjustable to anyone of arseries'of lapping positions parallel to one anotheriandgclosertol or farther away from a certain radius ofthe wheel, so that the greater the distance from the said radius the greater the angle of lapping obtainable by reason of the lapping being done on the contour of the wheel.

9. A machine as set forth in claim 8 wherein the abrasive material on the belt is finely divided silicon carbide.

10. A machine as set forth in claim 8 having in combination therewith a table of figures representing different micrometer measurements in which there is correlated with the angle of lapping desired the predetermined micrometer measurement relating to the distance of said tool supporting means from the radius.

11. The combination recited in claim 8, wherein the means for driving said abrasive belt comprises a pulley on a driven shaft, the combination including a support for said shaft oscillatably adjustable on an axis parallel to a radius of the wheel and passing through the center of the shaft at the middle of the pulley,-and screw threaded adjusting means connected with said shaft support to adjust it slightly in either direction to secure straight running of the belt.

12. The combination set forth in claim 8, wherein the means for driving the abrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as to swing away from the wheel to apply tension to the belt, said base plate being oscillatably adjustable on an axis parallel to a radius of the wheel and passing through the center of the shaft at the middle of the pulley, and screw threaded adjusting means connected with said base plate to adjust it 7 slightly in either direction to secure straight running of the belt.

13. The combination set forth in claim 8 wherein the means for driving theabrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as; to swing away from said motor base relative to said base plate to release tension on the abrasive belt.

14. The combination set forth in claim 8 wherein the means for driving the abrasive belt comprises a pulley on the armature shaft of an electric motor, said motor having its base hingedly mounted on a base plate so as to swing away from the wheel to apply tension to the belt, said base plate being oscillatably adjustable on an axis parallel to a radius of the wheel and passing through the center of the shaft at the middle of the pulley, screw threaded adjusting means connected with said base plate to adjust it slightly in either direction to secure straight running of the belt, manually operable means for raising said motor base relative to said base plate to release tension in the abrasive belt, and manually operable means for applying frictional braking efiect on the wheel to stop it quickly.

15; The combination of claim 8 wherein said:

tool bit supporting means includes a slide on which the work is carried adjustable toward and away from the periphery of the wheel in a plane at right angles to the direction of adjustment 8 relative to the said certain radius of the wheel. .16.. The method of precision finishing carbide tipped tool bits on the arcuate contour of a suitably driven finishing wheel which consists in rigidly supporting for sliding feed movement a bit adjacent to and with its tip directed toward the periphery of the wheel and so that the bit lies exactly parallel to a radius of the wheel, and adjusting the support precisely at right angles to the first mentioned position to a precise position where the tangent to the wheel periphery equals the angle to which the tip is to be finished. 17. The method of precision finishing carbide tipped tool bits on the arcuate contour of a wheel which consists in rigidly supporting for sliding feed movement a bit adjacent to and with its tip directed toward the periphery of the wheel and so that the bit lies exactly parallel to a radius of the wheel, driving the wheel while it unyieldingly supports on its periphery an endless thin belt of abrasive material, and adjusting the support precisely at right angles to the first mentioned position to a precise position where the tangent to the wheel periphery equals the angle to which the tip is to be finished. KARL L. LINDMARK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 85,537 Sawyer Jan. 5, 1869 278,578 McLaughlin May 29, 1883 504,306 Norton Aug. 29, 1893 1,292,372 Reisch et a1 Jan. 21, 1919 1,528,685 Murphy Mar. 3, 1925 FOREIGN PATENTS Number Country Date 67,799 Austria Aug. 1, 1914 

